Technical Abstract:
Most hay producers realize that hays packaged in large-round or large-square bales are particularly sensitive to spontaneous heating, dry matter losses, and negative changes in forage quality. During the last two decades, this has become an important dilemma for hay producers because the cost and availability of labor has necessitated the adoption of large-round or large-square hay packages on many farms. As a result of these factors, there often is a need for proactive action to reduce or eliminate spontaneous heating during bale storage, thereby preserving the quality of valuable hay crops. A series of studies was conducted at the Marshfield Agricultural Research Station to evaluate the effectiveness of these preservatives for alfalfa-dominated hays packaged in large-round or large-square bales. Propionic-acid based preservatives were very effective in limiting heating and preserving forage quality within large-square bales. However, responses only were marginal, and difficult to interpret, for large-round bales. Although normal heating characteristics clearly were altered by acid treatment for large-round bales, overall positive effects on poststorage forage quality were very limited. This could be related to the greater size of the bale packages (relative to large-squares), differences in application methodologies between round and square (plunger-type) balers, acid application rates, or other factors. For large round bales, the potential to improve forage quality relative to cost of application was not especially favorable, and producers may find that diligence to achieve adequate field desiccation prior to baling, or use of oxygen-exclusion methods, such as wrapping in plastic, may be better alternatives for preserving moist hays.